This blog post was created by Colin Seftor, NASA GSFC

After experiencing the worst fire season on record last year and continuing to face extreme drought conditions in British Columbia, Alberta, and the Northwest Territories, Canada is bracing for what may be another year of severe fires.  Two pyrocumulonimbus (PyroCbs) have already been identified around Fort Nelson (one on 11 May and one on 13 May), and the continuing intensity and scale of the fires in the area have caused the evacuation of thousands of people. 

PyroCbs are “fire thunderstorms” that can lift large plumes of smoke high up into the air, often reaching the stratosphere.  The plumes can then travel long distances, affecting air quality in areas thousands of kilometers from their sources.   The location and movement of these smoke plumes are monitored using measurements from satellite instruments such as the Ozone Mapping and Profiler Suite (OMPS) aboard the NASA/NOAA Suomi-NPP, NOAA-20  and NOAA-21 satellites.  The OMPS instruments, while primarily designed to determine the amount of atmospheric ozone, can also be used to detect atmospheric aerosols such as volcanic ash, dust, and smoke.  One particular OMPS product, the Aerosol Index (AI), is extremely useful for monitoring and tracking the movement of such aerosols because it can detect them over any type of land surface (including ice) and over clouds.

In the figure below, AI measurements from the Suomi-NPP OMPS instrument are shown overlaid on Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) true-color imagery for May 11-15.  Higher AI values (shown in yellow) represent higher density (and altitude) smoke plumes. The images acquired on May 11 and 12 show smoke being transported to northern parts of the United States, significantly impacting air quality in Minnesota and Wisconsin, where air quality alerts were issuedLarge sections of eastern Canada were also heavily impacted.

Figure 1: S-NPP OMPS AI values overlaid on true-color imagery from S-NPP VIIRS for May 11-13.  Smoke from fires burning in western Canada, particularly from two pyroCbs (one on May 11 and one on May 13) can be seen to affect large areas over Canada and the northern US.

Because of its usefulness in both detecting and monitoring smoke from fires, particularly large scale fire events and pyroCbs, the S-NPP OMPS AI is now included as an overlay in NASA’s Fire Information for Resource Management System (FIRMS) application, which provides near real-time active fire/hotspot locations using satellite-derived fire information to natural resource managers.  An example for May 11 is provided in the image and link below:

Figure 2: Screenshot of FIRMS US/Canada showing OMPS AI overlain on the Corrected Reflectance Imagery from S-NPP for May 11,2024. Active fire/hotspots are ovelain as red dots. See: NASA FIRMS US/Canada

Besides the S-NPP OMPS Aerosol Index, the AI measurements from the OMPS instruments on both the NOAA-20 (N-20) and NOAA-21 (N-21) satellites will be implemented in FIRMS later this year.  Both N-20 and N-21 AI measurements have the distinct advantage of being taken at a higher spatial resolution. The figure below shows the detail provided by the N-21 AI measurements for May 13 (right) when compared to the S-NPP AI (left).

Figure 3: Comparison of AI measurements from S-NPP (left) and NOAA-21 (right) OMPS instruments. AI products generated from N-21 have a higher spatial resolution (10km x 10km in the nadir direction - looking straight down from the spacecraft), which is 25 times more resolute than the (50km x 50km resolution) S-NPP AI products, providing a much greater level of detail for the smoke plumes.

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